From the 1966 Jane Eyre spin-off novel Wild Sargasso Sea to Ridley Scott's cinema release Prometheus, the prequel has been a much-used narrative device. And now US television is set to utilise the genre that was once only the domain of sci-fi. Two offshoots from Silence of the Lambs are pencilled in for 2013. There's NBC's Hannibal, which tells the life story of Dr Lecter before he developed a taste for fava bean and chianti surprise, and Lifetime's Clarice, which joins our heroine just after she has solved the Buffalo Bill case and graduated from the FBI. Rival US network A&E, meanwhile, is bringing out Bates Motel. The series will attempt to piece together the nascent personality of Norman Bates, prior to his Psycho days.

While these dramas are still in production, the trailer for Sex and the City prequel The Carrie Diaries (due to be screened in January 2013) hit the web last month and immediately highlighted the wisdom of the TV prequel genre. With its hammy script and am-dram acting, it made Gossip Girl (which shares the same producer) look like Borgen in comparison.

As with Silence of the Lambs and Psycho, Sex and the City is a franchise that has been adhering to the law of diminishing returns, with each new addition to the canon taking away from the impact of the original. Aside from the well-worn truth that Hollywood has run out of ideas, they suggest an innate defiling of the source text, substituting nuance in favour of highlighting the obvious and making what was once subtle become bloated. For fans of the original, it is the television equivalent of ditching the actual reading of a novel, and heading straight to the Wikipedia plot summary instead.